Extracorporeal circuits are known of a type referred to as “open”, which comprise a venous branch for blood collection, at least a rigid reservoir superiorly connected to the atmosphere and at least a return line of the treated blood (for example filtered and/or oxygenated) to the patient.
This first type of circuit using a rigid reservoir exhibits the drawback of typically offering a large contact surface between the free surface of the blood in the reservoir and the air, with a consequent possibility of activation of the air-blood contact and therefore the development of reactive phenomena on the part of the patient, which might initiate inflammation, activation of complement and coagulation, certainly undesired during extracorporeal circulation.
Together with the above-described “open” systems using a rigid reservoir, extracorporeal circulation system of the “closed” type are widely known.
The closed types comprise a venous line of the patient's blood, at least a bag able to contain a predetermined blood quantity, and a return line of the treated blood to the patient.
Thanks to the use of closed bags, there is the advantage of reducing to a minimum, and almost eliminating, the contact between the air and blood.
The disadvantages of the closed type systems are primarily connected to the greater operating complexity thereof due to the presence of an additional module (bag) connected by means of a line to a rigid reservoir containing the filtered blood; secondly, any air bubbles that might be present in the venous line are not automatically eliminated as the bag is a closed reservoir and therefore in order to separate and liberate externally any air trapped in the bag, it is necessary for the bag to be provided in a high part thereof with a breather valve.
Should the venous line be carrying numerous air bubbles, there is further the risk that the deformable bags might accumulate an excessive quantity of air.
In this case the circulation pump typically present, downstream of the bag, might aspirate one or more air bubbles present in the bag itself, sending them to the patient, with very grave consequences for the patient.
A system reducing the drawback constituted by air bubbles that might be present in the venous line includes using defoaming membranes, and maintaining an adequate level of blood in the bag, as well as placing the bag in contact with the air through a breather line.
Definitively, the known systems exhibit either the drawback of exhibiting a relevant contact zone between the blood and the air or a certain degree of inefficiency in the separation and consequent sure evacuation of the air bubble that might have collected in the venous line of blood aspiration from the patient.
Apart from the above-described drawbacks, the systems of known type exhibit a poor functionality and poor ability to adapt to various types of treatment, as the operator each time has to use a new circuit such as to respond to treatment requirements or treatments that time by time are to be applied.
In this situation, an aim of the invention is to obviate one or more of the drawbacks and/or limitations described herein above.
In particular, one of the aims of the invention is to provide a reservoir and an extracorporeal circuit using the reservoir which are able to provide greater flexibility with respect to the solutions of known type.
A further aim of the invention is to provide a technical solution which enables minimizing, as far as possible, contact between blood or other blood derivatives and the air.
A further aim is to provide a technical solution able to allow accumulation of relatively important quantities of blood externally of the human body during operating stages which for example comprise evacuation from the human body of significant quantities of blood or another biological fluid.
A further aim of the invention is to provide a technical solution which enables efficient filtering of the aspirated blood coming from the operating field.
A further auxiliary aim is to provide a solution in which the venous blood of the patient directly reaches the collecting device while receiving a suitable de-foaming action.
A further auxiliary aim of the invention is to make available a technical solution able suitably to treat, for example by oxygenation, the blood to be returned to the patient subjected to treatment.
One or more of the above aims, which will better emerge during the course of the following description, is substantially attained by a collecting device and an extracorporeal circuit using the device, according to one or more of the accompanying claim.